I can't remember where I stumbled on it, I think it came across on Twitter from John Gruber of Daring Fireball. Apple recently published a guide for securing Mac OS X Leopard appropriately named Mac OS X Security Configuration [PDF]. It's definitely not aimed at casual Mac-Heads, but seasoned veterans of the command-line, administrators of Mac OS X desktop and server environments and power-users will all benefit from this guide, which takes you through security from the ground up, recommending a fresh install from scratch even on systems that come with a pristine installation from the factory on a new Mac.The reading is somewhat dry, and it's basically a very long step-by-step guide with a brief explanation of why certain settings are being used. If you're looking for security theory, look elsewhere. If you want to know what default settings are secure and which are not, feel free to browse. It's logically organized. If you're a security-savvy Mac geek, this guide is worth the time to review.